<html>
<head>
  <style>
    #outer {
      position: absolute;
      top: 0px;
      left: 0px;
      height: 300px;
      width: 300px;
      overflow: auto;
      background-color: green;
    }

    #inner {
      background-color: blue;
    }

    #overlap {
      width: 500px;
      height: 500px;
      background-color: yellow;
    }
  </style>
</head>

<body>
  <div id="outer">
    <div id="inner"></div>
  </div>
  <div id="overlap"></div>
</body>
</html>
